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In July 2012 American businessman Russ George, dumped 100 tonnes of iron in the ocean off British Columbia to encourage plankton growth and thus increase salmon stocks (link). It is now claimed that this has increased the salmon catch by over 100,000 tons.

About 20 months ago, an American businessman conducted a massive ocean fertilisation test, fertilizing around 100 tonnes of iron sulphate off Canada's coast, it has emerged the Canadian government may have known about the geoengineering scheme and not stopped it. Satellite images confirmed the claim by Californian Russ George that the iron has spawned an artificial plankton bloom as large as 10,000 square kilometres. Now it appears that the fish catch in the area was boosted by over 100,000 tons.

How credible is this? The second link mentions a connection between volcanic ash and salmon numbers which would seem to lend some credence but is this generally accepted?

The climate change tag is because ocean fertilisation has been proposed as a way of trapping CO2, although the current claim is a bit different.

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    @Geobits The second link has a graph showing large year to year variations in catches which I haven't checked but have no reason to doubt. Given these large variations I would want to see some proof of the connection between the iron fertilisation and the harvest. – ChrisJP Jun 23 '14 at 17:47
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    I don't know about this test but iron fertilization of the ocean as a means of dealing with CO2 has been tried and fails. Yes, you get CO2 uptake--but you get some methane production (from decay) that removes the benefit. – Loren Pechtel Jun 23 '14 at 18:15
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    It's problematic to attribute causation to this. We might be able to confirm that the salmon catch increased but we can't say for sure what the cause was. Perhaps the ocean currents changed that year or perhaps storm blew some other nutrient out to sea etc. You'd need to select a number of locations then randomly choose a number of them to do the intervention. Unfortunately the standard deviation on a single event is one. – Murphy Jul 14 '15 at 14:26
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How credible is [the claim that salmon catch has increased by over 100,000 tons]?

Let us examine both the weight and number of salmon (see ADF&G Press Releases) per year.

The fertilization was conducted in 2012. Salmon numbers are expected to fluctuate and differ for even and odd years due to the two-year spawn times of pink salmon.

For each year, the harvest of the salmon industry in Alaska is recorded by the Alaska Department of Fish and Game. For 2013, a record high of 272 million salmon was recorded. For 2015, the salmon industry also fared particularly well with 263.5 million salmon. For even years, salmon catches are lower. In 2014, the 360,000 ton harvest was comprised of 156.4 million salmon. 2016 was a record-low harvest of 110 million salmon.

The last odd-year and even-year harvests prior to the fertilization event yielded 177 million salmon and 127 million salmon for 400,000 tons and 330,000 tons, respectively.

Comparing odd years, the harvest increased by 128,000 tons. For even years, the harvest increased by 29,000 tons, which does not appear to stand out among the normal fluctuation in years.

Yes, the salmon catch increased by over 100,000 tons for the immediate odd-year harvest.

As @Murphy has pointed, correlation does not imply causation. This is 1 event, and there are natural variations in salmon levels. 13 ocean iron fertilization experiments have been conducted since 1990 (source and source) and they have primarily focused on phytoplankton levels, not salmon levels. In the Nature news article, the director of the Millennium Institute of Oceanography in Concepción, Chile is quoted as saying "[The research foundation] claim that by producing more phytoplankton, they could help the recovery of the fisheries...We don’t see any evidence to support that claim."

The second link mentions a connection between volcanic ash and salmon numbers which would seem to lend some credence but is this generally accepted?

The link between volcanic ash and salmon numbers is poorly understood. According to the National Park Service, "the longer-term effects [of volcanic activity] are also generally negative." Articles that have mentioned volcanic activity and salmon levels (in particular around 2010) are all completely theoretical.

Further study is needed before making a connection between volcanic activity and salmon levels.

Note: While this question may have been asked in June 2014 , it's still interesting to consider the implications of such iron releases. As recently as May 2017, this topic has still been proposed. Thus, an answer may be warranted.

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    No need to excuse yourself for a late answer. This is exactly what Stack Exchange is for! – pipe Mar 6 at 9:13
  • "Long-term effects" is where the vast majority of human interference with nature turned out to be a bad idea. Of course there can't be studies regarding long-term effects of artificial fertilizing swaths of ocean, I just wish there were... oh, and, enjoy your Revival badge. Good find! – DevSolar Mar 6 at 14:29
  • @Brythan Good catch! I cannot believe I let that typo slip through. Thanks for the help. – Barry Harrison Mar 8 at 7:00

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